JP3011796B2 - Internal gear pump for hydraulic fluid - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The invention relates to a gear pump according to the preamble of claim 1.

[0002]

2. Description of the Related Art A pump as described above is known from DE-OS 344.
8253 (pp-1372).

[0003] The external gear is supported in a notch of the rotor. The rotor is also rotatably mounted in and fills a chamber formed by the internal gear. Known pumps have a perfect cylindrical inlet chamber located in the end wall as inlet and a passage system arranged in the rotor, which are always in communication.

This arrangement is only advantageous if the entire inner chamber, which is limited by the addendum circle of the internal gear, is filled by the rotor as long as it is outside the tooth meshing area.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an internal gear pump which is not provided with a rotor but is provided with an external gear which rotates eccentrically, and further, an inlet is provided with a tooth of a discharge side. The design is such that the entire meshing region does not short-circuit with the inlet region, and thus is entirely used as the delivery and discharge chamber.

[0006]

The above object is achieved by the features of claim 1.

[0007]

In the configuration according to the present invention, the meshing area is covered by the gear rotating the annular inlet chamber so as not to be connected to the inlet on the discharge side.

[0008] The configuration according to claim 3 and in particular according to claim 4 ensures good lubrication and cooling on both sides of the eccentric which is still loaded. It is also important that the pressure is balanced for the eccentric mounted on the plain bearing.

According to the fifth aspect of the present invention, it is possible to prevent the rotating force generated by the rotation of the external gear and the discharge region from acting on the drive shaft and causing the shaft to bend and the external gear to tilt.

According to the configuration of claim 6 and / or 7, good cooling and lubrication of the eccentric body is achieved, and the eccentric body is thermally and frictionally loaded on the inside and outside by the sliding bearing portion.

[0011] Further enhanced cooling is achieved by the measures of claim 8.

[0012] In a special configuration according to claim 9, it is advantageous if the discharge characteristic curve of the pump is such that it rises rapidly with increasing speed, then becomes constant and then falls again. Such a characteristic curve is particularly suitable for automotive hydraulic systems.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A pump casing has a casing peripheral wall 1 and an end wall.
And casings 2 and 3
Wall and the end walls are overlapped with each other in the axial direction of the drive shaft 16. The casing peripheral wall 1 has a true circular cylindrical inner chamber,
An annular groove 4 is cut into a cylindrical inner peripheral surface of the inner chamber. An internal gear 6 is fixed to the web 5 left on the side. The entire package consisting of the casing peripheral wall 1, the end plates 2, 3 and the internal gear 6 is held together by a screw connection 7. The screw coupling member 7 penetrates the internal gear in the region of the tooth tip by a hole 8.

The internal gear has internal teeth. The inner chamber of the pump is limited by the addendum circle 9 of the internal gear by the internal teeth. A pin 10 is fixedly inserted into the end plate 3 with one end. The other end of the pin 10 protrudes into the inner chamber of the pump. An eccentric body 11 is rotatably supported on the pin 10. The axial width of the eccentric body is substantially equal to the axial width of the casing peripheral wall 1 and the internal gear 6. The eccentric body has a perfect cylindrical outer peripheral surface, and its central axis is indicated by reference numeral 12. The eccentric body rotates around the axis 13 of the pin 10 with an eccentricity E. An external gear 14 is rotatably supported on the eccentric body 11. The external gear 14 has external teeth. The eccentricity E of the eccentric body and the external teeth of the external gear are designed so that the external teeth of the external gear mesh with the internal teeth of the internal gear, and the tooth profile is formed.

Accordingly, the addendum circles 9 and 15 of the tooth profile intersect at the rotating intersections 21 and 22. As a result, a meshing area is formed on the inner peripheral surface of the addendum circle 9 of the internal gear between the intersections 21 and 22, which rotates on the side of the axis 13 on the side where the eccentricity E is located, and on the other hand, the eccentricity of the axis 13 on the other side. On the opposite side, a rotating crescent space 23 of the pump is created.

The tooth profile is formed such that the teeth of the internal gear and the external gear mesh closely with the tooth surfaces between the intersections 21 and 22 of the addendum circles 9 and 15. Therefore, the intersections 21 and
In the area of engagement between the two, a plurality of displacement chambers are created, which are sealed by contact of the tooth surfaces with respect to each other and to the crescent space 23 on the side opposite to the eccentric side.

A drive shaft 16 is used to drive the pump. The drive shaft 16 is rotatably mounted in the other end plate 2 concentrically with respect to the axis 13 of the pin 10 and its end terminates substantially in line with the inner surface of the pump chamber. I have. Here, the drive shaft 16 forms an end face, and the connecting piece 17 is eccentrically fixed to this end face. This connecting piece 1
7 projects axially into the entrainment pocket 18, which is formed in the end face of the adjacent eccentric 11 in an eccentric region.

The pump has a substantially radial inlet passage 19 in the end plate 3 as an inlet. Inlet passage 20
And the distribution chamber concentrically surrounds the pin 10. The distribution chamber is formed as a perfect cylindrical cutout in the end face of the end plate that limits the pump chamber. The radius of the distribution chamber is smaller than the radius FJ of the root circle of the external gear.

On the end face of the end plate 2 on the opposite side, another true circular cylindrical notch is formed concentrically with the axis 13. This notch is used as the entrance chamber 28. The distribution chamber 20 and the inlet chamber 28 are connected to each other by a passage. The passage extends axially through the eccentric. These passages are preferably formed as slots in the eccentric body and are used for lubricating the eccentric sliding bearing on the pin 10 and cooling the eccentric body 11. The entrainment pocket 18 is used as such a passage, so that the entrainment pocket extends axially through the eccentric 11 and its outer edge lies on a circumference with a radius slightly greater than the radius of the shaft. It is particularly advantageous for this passage to be on the eccentric side of the eccentric axis. This is because there is also a discharge side on this side, so that the eccentrics are exposed here, in particular, to pressure, friction and thus heat loads. Heat can be removed from this axial passage located in the eccentric region. Further, a plurality of such passages may be provided. Additionally or alternatively, the axial passage can be used to improve lubrication of the plain bearing. These passages are used for lubricating the sliding bearing of the external gear on the eccentric and also for the sliding bearing of the eccentric on the fixed pin 10. FIG. 2 shows two further such lubrication passages 29 in the plain bearing area of the external gear. Lubrication passage 29 is eccentric 1
1 are shifted by 60 ° in the circumferential direction. Suitable passages can also be provided in the bore of the eccentric, so that the oil flow through these lubricating passages 29 and the entrainment pockets 18 provides a symmetric distribution of the oil and at the same time a hydrodynamic support of the eccentric. However, this oil flow also has the effect of cooling the eccentric body. This cooling action is particularly important since the eccentric body itself is rotatably supported in the bore and the outer peripheral surface is used as a rotatable support for the external gear.

Another means of cooling, which is additionally
Or can be used instead) is an annular passage,
That is, the eccentric body on the side of the inlet chamber 28 and / or the distribution chamber 20 is slightly thinner than the internal gear or the inner width of the casing peripheral wall 1. In this case, an annular surface is formed at the end face of the eccentric, which is filled with oil, and where a continuous oil flow occurs. This configuration of the eccentric is shown in FIG. 3 by lines 34 and 35, which show the end faces of the eccentric.

The radius R of the outer diameter of the inlet chamber 28 (relative to the axis 13 of the pin 10) must be kept within a certain range according to the invention, which will be described later. The radius R of the outer diameter of the inlet chamber 28 is designed such that the root area FJ of the external gear or the circle area surrounded by the root circle covers the inlet chamber 28 except for the crescent-shaped inlet surface 27. . Part of the inlet face is also covered by the tooth side of the external gear. The inlet surfaces rotate together on the opposite side of the inner chamber from the eccentric side.

Due to the design according to the invention of the radius R of the outer diameter of the inlet chamber 28 on the one hand and the root circle FJ of the external gear on the other hand, the crescent-shaped inlet face 27 is provided by one of the closed displacement chambers in the meshing area. Uncovered is achieved. This avoids the dead distance of these displacement chambers in the discharge area and improves the hydraulic efficiency.

The outlet passage 24 is located radially in the casing peripheral wall 1 and is connected to the peripheral groove 4 of the casing peripheral wall. This circumferential groove is limited on the inside by the outer peripheral surface of the external gear and forms an outer chamber.

The internal gear has at least one tooth in the area of each tooth groove.
It has two outlet holes 25. FIG. 1 shows that two outlet holes 25.1, 25.2 are arranged axially in each tooth slot. The outlet holes are each arranged in a parallel radial plane. Each radial plane is covered by a resilient valve ring 26.1, 26.2, which covers all outlet holes in the vertical plane and is divided in the axial plane. One end of the valve ring is fixed by, for example, a rivet, and the other end is freely movable.
These valve rings 26.1, 26.2 serve as check valves for each outlet hole.

Next, the operation will be described.

The drive shaft 16 is driven in the direction of rotation indicated by the arrow 31. At this time, the connecting piece 17 engages with the entrainment pocket of the eccentric body and entrains the eccentric body. This causes the external gear to wobble in the inner chamber of the pump, and the external gear rotates in the direction indicated by arrow 32 as a result of the engagement of its tooth with the tooth of the internal gear. The external gear together with the tooth profile of the internal gear forms a plurality of displacement chambers between the intersections 21 and 22 of the addendum circles, and the displacement chamber continuously expands and contracts. In the subsequent area, the displacement chamber expands until it opens and communicates with the oil-filled crescent chamber. On the leading side of the external gear, the displacement chamber shrinks. Thus, here the oil is placed under pressure. If the pressure in the displacement chamber exceeds the prevailing system pressure in the channel 4, the valve rings 26.1 and 26.2 are now lifted from the outlet holes 25.1, 25.2 due to the pressure difference, The resulting oil can squirt from the displacement chamber.

Due to the negative pressure created on the inlet side, oil is distributed in the distribution chamber 2
It is sucked from the inlet chamber 28 through 0 and lubrication passage 2 9 entrained in parallel beauty pockets 18 on the outer peripheral surface of the pin 10 from the inlet passage 19. As a result, a good lubricating film is formed in the range of the sliding bearing of the eccentric 11, which is simultaneously used for lubrication and also for hydrodynamic support.

The outer diameter of the inlet chamber 28 is designed so that the displacement chamber is not connected to the inlet chamber 28 on the discharge side.
Inlet chamber 28 by the end face of the external gear in the discharge region, i.e., the area bounded by the dedendum circle is covered by a surface described by the tooth apex. The peripheral surface of the inlet chamber 28 at the outer Accordingly, and in the inner with the outer teeth crescent limited by the dedendum circle of the gear width of the inlet surface 27, the crescent limited by Ryoha tip circle of the internal chamber 23 At most than width
It may be larger by the pitch angle of the gear 6 . However, the width and pitch of the <br/> crescent inlet surface 27 and inner chamber 23
The angles are each determined as a central angle with respect to the central axis 13 of the pump.

The pump can also be used advantageously as a pump which is throttled on the suction side. In this case, the inlet passage 19 is provided with a throttle 33. Only the time-limited amount of oil can be sucked in for this restriction. The time-limited suction volume is sufficient to completely fill the pump up to a predetermined number of revolutions. Therefore, the discharge amount of the pump is proportional to the rotation speed up to this rotation speed. An increase in the rotational speed no longer leads to a further increase in the output. Therefore, an increase in engine speed does not translate into increased oil consumption. The pump is therefore suitable for motor vehicle actuators having a required oil quantity which is not influenced by a significantly fluctuating engine speed.

Instead of, or in addition to, the throttle 33 in the inlet passage, the inlet face 27 may be designed so small that the throttle action necessary for adjusting the suction volume is performed. As a result, the seal member 36 in the range between the drive shaft 16 and the casing end plate 2 may be free from the load of the pressing force.

The radius of the distribution chamber 20 can be determined in the same way as the radius of the inlet chamber 28. In this case, the filling of the pump takes place both via the distribution chamber and via the inlet chamber. In this case, at the suction-side throttle, a discharge characteristic curve which first rises steeply with the rotation speed, but then becomes constant irrespective of the rotation speed is obtained. Such a characteristic curve is suitable wherever a constant hydraulic power has to be applied, independent of the engine speed and the speed of the vehicle, in the hydraulic system of the vehicle.

However, the radius of the distribution chamber can also be designed such that it does not communicate with the discharge chamber formed by the teeth. In this case, the filling of the pump takes place exclusively via the inlet chamber 28. In this case, the throttle on the suction side of the pump first rises steeply with the number of revolutions, then breaks, and is initially almost constant over the range of revolutions,
Next, a discharge characteristic curve that falls again with the rotation speed is obtained. Such characteristic curves are used in the field of automotive hydraulics.
Wherever only reduced hydraulic power at high vehicle speeds or engine speeds has to be applied, this is appropriate, for example, as in steering assist systems.

[Brief description of the drawings]

FIG. 1 is a sectional view including an axis of a pump.

FIG. 2 is a cross-sectional view of the pump according to FIG. 1;

FIG. 3 is a view corresponding to FIG. 1 of a pump in which the end faces of the eccentric body have different configurations.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Casing peripheral wall 2, 3 End plate 4 Groove 5 Web 6 Internal gear 7 Screw connecting member 8 Hole 9 Tooth circle 10 Pin 11 Eccentric body 12 Center axis 13 Axis 14 External gear 15 Tooth circle 16 Drive shaft 17 Connecting piece 18 entrained pocket 19 inlet passage 20 distribution chamber 21, 22 intersection 23 crescent chamber 24 outlet passageway 25.1,25.2 exit hole 26.1, 26.2 valve ring 27 inlet face 28 inlet chamber 2 9 lubricating passageway 31,32 Arrow 33 Aperture 34, 35 End face 36 Seal member

Continuation of the front page (56) References JP-A-56-118582 (JP, A) JP-B-33-737 (JP, B1) West German Patent Application Publication No. 348459 (DE, A1) West German Patent Application Publication 3504783 (DE , A1) (58) Field surveyed (Int. Cl. ⁷ , DB name) F04C 2/10 331-341

Claims (9)

(57) [Claims] An internal gear pump for hydraulic fluid, wherein an internal gear having internal teeth is fixed concentrically with the pump axis.
And placed adjacent to both sides of the internal gear in the axial direction of the pump.
Form a closed inner chamber with a pair of end walls ,
A relatively small external gear having external teeth rotates eccentrically with respect to the internal gear around the driven eccentric body (11) and meshes with the internal gear, and the internal gear ( 6) and an external gear (14) at least two differences in the number of teeth of, and the inlet is provided in the end wall, a concentric true circle cylindrical inlet chamber internal gear cage, the outer diameter of the inlet chamber radius,
Smaller than the sum of the eccentricity and the external gear of the dedendum radius with respect to the pump axis of the eccentric body, and in that the larger format than the difference of the radius and the eccentricity of the dedendum of the external gear, the external teeth A gear (14) partially covers the inlet chamber (28) and releases the rotating crescent shaped inlet surface (27), which extends over a central angle measured at the pump axis (13). and has a <br/> pitch angle of the center angle the internal gear (6), crescent chamber for rotation that has been limited by both the tip circle opposite the eccentric side of (23), a pump axis (1
An internal gear pump for hydraulic fluid, characterized in that it is smaller than the sum of the central angles measured in 3). 2. An outlet, in each case in the meshing region between the points of intersection of the addendum circles, in which a plurality of teeth pairs mesh closely and form closed displacement chambers and are closed in each tooth groove by a check valve. The pump according to claim 1, wherein a passage (25) is assigned and a plurality of outlet passages are each assigned to the discharge chamber (4). Wherein the eccentric body (11) is an inlet chamber in one end (28)
To, and in other end is in contact next to a perfect circle cylindrical distribution chamber (20), the distribution chamber is connected to the inlet passage, and the radius of the outer diameter smaller than the radius of the dedendum circle of the external gear the has, and the distribution chamber (20) and inlet chamber (28) is connected by a passage parallel axes (18, 2 9), according to claim 1 or 2 pump according. 4. An eccentric body whose axis is parallel to the path ( 18 , 29 ).
4. The pump according to claim 3, wherein the passage is pierced by an eccentric region. 5. The eccentric (11) is rotatably mounted on a pin (10) fixedly and cantilevered in the housing and concentric with the axis (13) of the pump. Item 5. The pump according to any one of Items 1 to 4. 6. A passage parallel axes (18, 2 9) of the slide bearing section of the eccentric body on the pin and (or) formed in the form of respective axially only in the sliding bearing portion of the external gear on the eccentric body The pump according to claim 5, wherein 7. The pump according to claim 5, wherein the eccentric is narrower on the side of the inlet chamber (28) and / or on the side of the distribution chamber (20) than the external gear (14). 8. An eccentric body is connected to the drive shaft via an eccentric drive body (connection piece 17) of the drive shaft, and the drive body is engaged with the notch (drive pocket 18), 6. The pump according to claim 5, wherein the entrainment pocket serves as a passage between the inlet chamber (28) and the distribution chamber (20). 9. The distribution chamber (20) has a radius smaller than the difference between the radius of the root of the external gear (14) and the eccentricity (E) of the eccentric body (11). The pump according to any one of claims 1 to 8.